Khaled Sennah

Torsional stresses pose a critical challenge in reinforced concrete (RC) members due to their sudden occurrence and the associated risk of brittle, progressive failure, emphasizing the need for strengthening solutions that enhance both ductility and structural sustainability. Existing RC beams may suffer from inadequate torsional capacity owing to load redistribution, design limitations, structural modifications, or the introduction of openings, necessitating effective and reliable strengthening solutions. This study investigates the behavior of anchored ferrocement layers incorporating engineered cementitious composite (ECC) and ultra‐high‐performance ECC (UHPECC), reinforced with wire steel mesh (WSM), for enhancing the torsional exhibition of rectangular beams. A series of RC beams was experimented under pure torsion, studying the influence of composite type (ECC vs. UHPECC), ferrocement thickness (10, 20, and 30 mm), WSM layering (one vs. two layers), and anchorage quantity (four vs. six steel anchors). The experimental results revealed that UHPECC thickness and WSM layers had the greatest impact on the initial cracking load. The evaluated parameters were found to significantly improve the cracking response, ultimately leading to a ductile failure mode with up to a 94% increase in torsional capacity. Results showed that beams with UHPECC outperformed those made of ECC, increasing the torsional capacity, stiffness, and energy absorption capacity by 63%, 153%, and 211%, respectively, compared to the defective beam, whereas the application of ECC improved the torsional capacity, stiffness, and energy absorption capacity by 46%, 125%, and 121%, respectively. Also, increasing the ferrocement thickness from 10 to 30 mm improved ultimate torsional strength by 147%. Furthermore, incorporating two WSM layers enhanced torsional capacity, stiffness, and energy absorption capacity by 140%, 247%, and 267%, respectively, compared to the defective beam, demonstrating improved crack control and stress redistribution. Moreover, six steel anchors provided better bond strength than four, preventing debonding and improving load transfer, resulting in an increase of the torsional capacity, stiffness, and energy absorption capacity by 63%, 153%, and 211%, respectively, compared to the defective beam. Complementary numerical analyses were performed on the tested beams, yielding a refined finite element model capable of accurately simulating the torsional response of rectangular sections. The numerical predictions closely matched experimental results, with an error of only 6%.

This study introduces an innovative approach to strengthening defected reinforced concrete (RC) columns using externally bonded stainless steel and galvanized steel plates. Unlike conventional strengthening methods, this technique replaces traditional transverse stirrups with steel sheets, providing enhanced confinement and ductility. The experimental program involved static load testing to collapse a series of RC columns, including a master column with adequate transverse reinforcement and defected columns with reduced stirrups to simulate structural weaknesses. The defected columns were strengthened using stainless steel and galvanized steel plates in arrangements to evaluate the influence of different plate configurations (three‐layer vs. four‐layer) and volume ratios (2% vs. 3%) on structural performance. Experimental results show that strengthening with a 3% ratio of stainless steel plates increased the ultimate load capacity by up to 66%, while galvanized steel plates achieved a 58% improvement. The ductility of strengthened columns improved compared to the defected columns. The energy absorption capacity increased significantly, with the four‐layer stainless steel configuration achieving a 370% enhancement over the unstrengthened specimen, with a slightly lower value for galvanized steel plates. In addition, a finite element model was developed to simulate the performance of the tested columns. The finite element modeling accurately captured the experimental failure modes and load–displacement behavior, validating the effectiveness of this strengthening approach. A parametric study was conducted to investigate further the relationship between sheet thickness and ultimate load‐bearing capacity. The study provides practical insights for optimizing plate configurations to balance structural performance and material efficiency, offering a cost‐effective solution for enhancing aging or under‐designed RC structures. These findings demonstrate that using stainless steel and galvanized steel plates is a viable alternative for strengthening RC columns, particularly for seismic retrofitting applications.

This study investigates the structural performance of TL-5 concrete bridge barriers reinforced with glass fiber-reinforced polymer (GFRP) bars at the critical deck–wall interface. Five full-scale barrier models were subjected to static load testing until failure. The wall reinforcement included four barriers with high- and standard-modulus GFRP bars using headed-end, bent, and hooked anchorage, and one with conventional steel reinforcement. The objective was to assess the load-bearing capacity, failure modes, and deformation behavior of GFRP-reinforced barriers with respect to the Canadian Highway Bridge Design Code (CHBDC) requirements. Results revealed that all GFRP-reinforced models achieved ultimate flexural capacities surpassing CHBDC design limits, with diagonal tension cracking at the corner joint emerging as the predominant failure mode. A set of new equations was developed to predict diagonal tension failure and determine minimum reinforcement ratios to mitigate such failure. Comparisons with experimental findings validated the proposed analytical approach. Among the configurations tested, barriers with headed-end high-modulus GFRP bars offered the most cost-effective and structurally sound solution. These findings support the incorporation of GFRP bars in bridge barrier design and establish a framework for future code development regarding GFRP-reinforced barrier systems.